Hydraulic lash adjusters are used in valve trains of internal combustion engines to accommodate valve lash, as well as, in certain applications, to control valve lift modes. Internal combustion engines include cylinder heads in which the lash adjusters are typically arranged which have hydraulic fluid galleries that feed pressurized hydraulic fluid to ports defined in a housing of the hydraulic lash adjuster. A plunger is arranged within a bore of the housing and is axially displaceable to perform the hydraulic lash adjustment as well as optionally a switching function to provide a partial or zero lift opening of the associated valve. When the switching function is provided, a port of the housing feeds hydraulic fluid into a chamber of the plunger which directs the hydraulic fluid to an open-ended nose portion and actuates a switching function of the rocker arm or finger lever assembly between first and second valve lift modes.
A significant amount of pressure loss occurs when the hydraulic fluid flows from the hydraulic fluid gallery of the cylinder head to a space defined between the cylinder head and an outer surface of the outer housing. Pressure loss is particularly high when the port of the housing is not aligned with the hydraulic fluid gallery in the cylinder head. One way to ensure that hydraulic fluid is quickly fed to the port on the housing is to provide a number of ports around a periphery of the housing. However, modifying the housing with multiple ports increases the costs and time required for assembly and formation, as well as reduces the strength of the housing. It is desirable to minimize the amount of time required to perform the switching function and to minimize the pressure loss when hydraulic fluid travels from the cylinder head gallery to the ports on the outer housing of the adjuster without compromising the strength of the housing or requiring a complex formation process.